Energy efficiency is increasingly important to operators of communications equipment. Network nodes, such as switches, bridges, routers, and the like consume substantial amounts of power even when such nodes are not actively processing data. This results in unnecessary energy consumption and costs. Communications standards, such as Institute of Electrical and Electronics Engineers (IEEE) 802.3az Energy-Efficient Ethernet, for example, are being developed to help address these issues.
Also of interest to operators is the current work on moving control and intelligence from individual switching, routing, and bridging nodes to a single controller node, as exemplified, for example, by a software-defined network (SDN). SDN is a network architecture wherein the forwarding plane (sometimes referred to as the data plane) and the control plane, which are conventionally implemented in a single network node, are separated and implemented in two distinct network nodes. Such distinct network nodes may be referred to as a datapath node and a controller node, respectively. An example of an SDN architecture, or specification, is the Open Flow Switch Specification, version 1.3.
Theoretically, by separating the forwarding function and the control function into different network nodes, multiple relatively inexpensive datapath nodes may be coupled together and controlled by a single controller node, resulting in an overall lower network cost. Another potential advantage of an SDN is that a single controller node can be more easily programmed to implement new network functionality than would be possible by programming multiple conventional network nodes that combine the control plane and the forwarding plane, thereby simplifying the implementation of additional networking functions in the network.
Although datapath nodes in an SDN may implement IEEE 802.3az energy-efficient algorithms, currently such algorithms are relatively simplistic, and are not based on the type of flow that the datapath node is processing. Centralized power-management functions for SDNs wherein the controller node directly controls when the datapath node enters or exits an energy-efficient mode have been proposed. Unfortunately, a centralized power-management function requires substantial signaling between the controller node and the datapath nodes, and is thus better suited for energy efficiency of relatively long-term periods of time, such as the period of time outside of normal business hours. A centralized power-management function that directly controls the datapath nodes may result in substantial network usage, and may also not be scalable to large networks with hundreds or thousands of datapath nodes. Moreover, different types of flows may be suitable for different types of energy efficiency policies. Accordingly, there is a need for more robust and flexible energy-efficient mechanisms, particularly in the context of an SDN network.